Electronic textiles (e-textiles) is an emerging interdisciplinary field of research that encompasses electronics, materials science, and textiles. E-textiles aim to integrate electronic circuits, sensors, computing elements, and communication into multi-functional textile products and/or apparel. By using textile processes, such as sewing, weaving, and embroidering, sensors may be fabricated upon or within flexible substrates that may be directly integrated into wearable garments. The e-textile approach has significant advantages over conventional sensors fabricated using traditional printed circuit boards in that these e-textiles are less bulky and may be made to move and/or stretch in the manner of the garment into which they are integrated.
Some e-textiles have been developed to detect motion, expansion, and/or contraction that is indicative, for example, of breathing in a wearer of the e-textile garment. In such existing e-textiles, strain gauge sensors are fabricated from polypyrrole (PPy) conductive yarns, or from carbon-filled rubber (CFR) coated conductive yarns. These yarns may be used to construct threads which may be woven or knitted to form a sensor within a textile substrate. While such conventional e-textile sensors exhibit piezoresistive properties when stretched, such sensors also exhibit some undesirable characteristics such as inconsistent loading and unloading properties due to quality control issues in weaving and/or knitting the “sensor” threads into the textile substrates. In summary, it may be difficult to form complex sensor patterns in e-textiles that utilize a knitted and/or woven fabric substrate wherein semi-metallized and/or metal conductive yarns are sewn into such substrates. Furthermore, processes for sewing conductive materials into a knitted and/or woven substrate are time-consuming and error prone, which adds to the complexity and cost of producing e-textile sensors and/or garments utilizing such sensors.
Thus, there exists a need in the art for an e-textile sensor system that addresses the shortcomings of the conventional e-textiles discussed herein. For example, there exists a need for a sensor system that allows for the formation of complex electrode and/or sensor components on or within a fabric substrate such that the sensor system is capable of providing stable, accurate, and precise data over time. In addition, there exists a need in the art for an e-textile sensor system that may be easily manufactured for a relatively low cost.